This invention relates generally to terrain mapping and more particularly to the generation of multi-dimensional topographical terrain models of the earth's surface such as forested regions which have an underlying surface which is periodically flooded or includes a water surface of varying elevation.
Wetland forests and Mangrove or wet coastal forest ecosystems are an important resource throughout the tropic and subtropic regions of the globe. As a whole, these formations account for a significant share of the forested coast lines and river flood plains of these regions and are an important source of biological productivity. By providing environments for abundant plant, algal, and marine and terrestrial animal life these ecosystems figure prominently in the cycling of organic matter.
A critical environmental factor in the formation, health, and status of these ecosystems is the surface hydrology, the two most important factors of which are the water level dynamics and water chemistry. Both of these factors are critically interactive with the geomorphology or substrate topography upon which flood plain forests and mangroves evolve. The topographic contour of the floor of these forests, moreover, determines the frequency of the flooding and the chemistry of the flood waters and thus the productivity and health of the forest and the utility of the soils.
Heretofore, generation of contour maps or obtaining terrain information of forested regions relied solely upon leveling survey measurements acquired on the ground. This meant that a team of surveyors actually had to enter the area and take required measurements. Aerial survey was impossible as the terrain is hidden by the forest canopy. Ground survey is a very tedious and expensive process that requires total and long term access to the area of interest. Also, many of the world's coastal forests, river deltas and flood plains are not readily accessible. These include the mouths of the Ganges river, the Amazon basin, the Mississippi delta, and the Mekong delta, to name a few. In addition to being very time consuming, such efforts are extremely tedious, require many people, extensive travel and logistics, and often access to the areas to be surveyed is impossible because they lie in a politically sensitive area.
While terrain modeling and foliage penetration using a synthetic aperture radar is generally known and can also be used to remotely determine water level given the use of special "in situ" devices, radar derived flood boundary maps combined with tide and hydrology data is not known to have been used to generate topographic models of subcanopy surface areas which periodically change due to the water surface variation caused by the changes in the water level in the region of concern.